Over the past decade, there has been an increasing worldwide demand for oil and gas production. At present, however, oil and gas supply continues to lag far behind demand, a situation which has at times contributed significantly to worldwide economic difficulties and could well present a major concern for many years to come.
In an effort to balance supply and demand, companies and governmental entities have begun to explore and develop relatively marginal fields in the deeper offshore waters of the Gulf of Mexico, West Africa and Brazil. However, due to high construction costs and limited manufacturing facilities, only a small number of mobile offshore drilling units (MODUs) are being manufactured each year, thereby resulting in escalating “per day” unit costs and a shortage of associated offshore drilling, completion and workover equipment.
Moreover, even though the cost differential between drilling operations and completion or workover operations is relatively modest (since MODUs usually perform all of these functions during a typical operation), most such projects are still inefficient, because a MODU actively performing one function (e.g., drilling) is generally not able to accomplish any other functions (e.g., completion or workover).
In other applications by this inventor, it has been shown that a self-standing riser system can be safely and reliably installed in communication with a well head or production tree. Such risers by design are self-supporting, and provide all of the necessary risers, casing, buoyancy chambers, etc., required for exploration and production and of oil, gas and other hydrocarbons. Self-standing risers also provide the requisite safety features required to ensure that the produced hydrocarbons do not escape from the system out into surrounding waters. For example, self-standing riser systems fully support both surface-based and semi-submersible platform interfaces, blow-out preventers, production trees, and other common exploration and production installations.
Known self-standing riser systems require either a number of different surface vessels or a MODU for installation, due to the size and weight of riser stacks, drilling pipe, buoyancy devices, etc. For many installations, expensive hull and deck modifications also have to be made. Accordingly, few improvements in associated per-day costs have been realized.
There is, therefore, a need for a more cost-effective method of installing self-standing riser systems, which does not require the use of MODUs.